Increased rainfall and vegetation changes result in sediment shifts at the Roof of the World

Researchers from the University are part of an international project exploring the impact of changes in the global climate
The clear Nyang River enters the muddy Yarlung Tsangpo River, showing different trends in sediment flux
Dr Zhiwei Li

The Qinghai-Tibet Plateau occupies an enormous area of Asia and is known as the Roof of the World, owing to an average elevation that exceeds 4,500m.
Located at the heart of the Himalayas, the plateau is home to the headwaters of several of the world’s largest rivers, including the Brahmaputra, Indus, Mekong, Yellow, and Yangtze.
However, new research by an international team of scientists has found that changes in the global climate are altering the behaviour of those and other rivers as they flow from the mountains towards some of the world’s most populated coastlines.
That is also influencing the huge quantities of sediment the rivers carry, and these changes are more varied than the research team had anticipated before they began their study.
Published in the journal Communications Earth & Environment, the study was carried out by joint team from the universities of Wuhan, Sichuan, Beijing Normal, Colombia, Edinburgh and Plymouth.

Previous studies on the sediment yield of the Qinghai-Tibet Plateau either employed process-based models, which require a large amount of data to calibrate parameters and so are confined to small watersheds, or relied on statistical models which fail to trace the complicated physical pathways.

By combining up-to-date methods, our model has enabled us to quantify sediment changes driven through the main physical pathways using data that are relatively straightforward to obtain at large scale.
Jinhao Guo
Wuhan University 

The effects of climate change are obviously of great importance in the Qinghai-Tibet Plateau, and to the environments and communities that line the rivers emanating from the plateau.

This study uses novel methods to assess sediment flux trends in river headwaters – the results show that sediment flux is changing greatly at several key locations due to precipitation, temperature, and vegetation effects. Our study has highlighted how opposing sediment flux trends on the Qinghai-Tibet Plateau are being driven by different aspects of climate warming.

Alistair BorthwickProfessor Alistair Borthwick
Professor of Applied Hydrodynamics

For the study, the researchers reconstructed 40-year sediment flux time histories using data generated at 25 hydrological stations on the Qinghai-Tibet Plateau. That information included shifts in surface and underlying soil erosivity, river discharge and vegetation cover, as well as levels of rainfall, meltwater and temperature.
Using a specially developed mathematical model, they found that sediment flux increases at five of the hydrological stations had been driven in large part by increases in both rainfall and temperature.
However, significant decreases at another seven stations were demonstrated by the model to be down to expansion of the vegetation cover.
The study’s authors report that this demonstrates the complex balance of power at play between some of the differing consequences of climate change, with sediment yield increasing in cold, dry areas where precipitation is accelerating, and decreasing in areas where the temperature is rising rapidly and precipitation is slowly increasing.
The authors believe their findings will benefit the understanding of environmental processes in other parts of the world, such as the Andes.

It was always mysterious for us that temperature and precipitation have both experienced rising trends in the Qinghai-Tibet Plateau during the past 60 years, but recorded sediment fluxes have exhibited opposing change trends. The increasing temperature and precipitation should have accelerated sediment yield by melting frozen earth and breaking more soil. However, the situation appears counterintuitive in several basins, and our method successfully solved the mystery by clearly presenting the contribution of each pathway chain.

Professor Yao Yue
Director of the research, Wuhan University
  • The full study – Guo et al: Original vegetation condition and precipitation growth rate bifurcate sediment flux trend on the Qinghai-Tibet Plateau – is published in Communications Earth & Environment, DOI: 10.1038/s43247-025-02075-w.
 

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Beautiful first light from sunrise on Mount Kanchenjugha, Himalayan mountain range, Sikkim, India. Orange tint on the mountains at dawn. Image courtesy of Getty Images.